More 3GIO, SCSI fireworks expected at IDF

SAN JOSE, Calif.  Interface debates will heat up on two fronts  system interconnects and disk drive interfaces  at the Intel Developer Forum (IDF) starting Monday (Feb. 25).

Intel Corp. will offer more details on its proposed 3GIO system interconnect, including radically new form factors enabled by 3GIO that could someday change the way OEMs build and consumers buy computers. But the powerful PCI Special Interest Group is expected to recommend that PCI-X 2.0 be used for servers in the short term, confining 3GIO at least in its early stages to desktop computers.

Separately, Intel will disclose Serial ATA II, a high-end interface primarily for hard-disk drives that is expected to double the speed of the yet-to-be-deployed Serial ATA to about 300 Mbytes/second. But the spec will compete with Serial Attached SCSI, an interface backed by a 20-company working group including Compaq, Dell, Hewlett-Packard and IBM.

So-called revo (revolutionary) form factors for 3GIO are only in the concept stage thus far and are not part of the proposed 1.0 specification that's expected to be handed over to the PCI Special Interest Group later this year by the Intel-led Arapaho Working Group. Nevertheless, new ideas for high-speed cartridge-like devices that could slide into systems have already sparked fresh thinking among designers about new ways to build computers.

Modular platform

"You could have systems that look very different," said one engineer close to the effort who asked not to be identified. "For instance, you could have a system with a 3GIO backplane in it and plug in 3GIO compute modules with processors and memory in them. It creates a more modular platform, where you can upgrade everything on the fly.

"One of the things we are looking at is a graphics module that slides into a flat panel. At some point you might even have a computer module that plugs into a TV as its monitor. These are things you can't do with PCI," the engineer said.

Such concepts could accelerate the commoditization of the personal computer, but they require agreement on the device sizes, connectors and signaling specs from a broad group of players  consensus the group has yet to win. Indeed, such agreement can be hard to come by. Several years ago Compaq, Microsoft and Intel promoted a similar concept  Device Bay  using a hybrid USB and 1394 interface, but the concept never got broad support.

"There's a lot of stuff we're going to need to get industry input on," said the engineer. "I don't think these ideas will be delivered in 2003; it's much further out."

Meanwhile, Intel is expected to disclose "evo," or evolutionary, form factors for 3GIO adapters that are more closely related to existing PCI adapter form factors, leveraging the current infrastructure as much as possible. Intel will also emphasize that 3GIO adapters will be backward-compatible with PCI software.

PCI-X 2.0 rollout

Some server and chip makers, however, are backing a rollout of PCI-X 2.0 in the near term. Server makers need to support 10-Gbit/s adapters for high-end Ethernet, Fibre Channel and other interfaces, said Doug Pulling, vice president of marketing for chip maker ServerWorks Inc., a subsidiary of Broadcom Corp. PCI-X 2.0 is the only available systems interconnect to handle such cards in the short term, he said.

ServerWorks expects to release a bridge chip this summer that will support PCI-X 2.0 for an upgraded version of the Pentium 4 using a 533-MHz front side bus.

Pulling said the PCI SIG will shortly roll out design guidance on using new interfaces, including a recommendation that servers adopt PCI-X 2.0 and that desktops migrate to 3GIO, he said.

The PCI SIG is expected to advise Monday that PCI-X 2.0 be recommended for use in servers for both the short and long term and that 3GIO eventually be recommended for use in all computing segments, although it may not be available for use in servers until products that ship in 2004 or later. The nature of the exact wording on the guidelines is said to be controversial because SIG members have different views on the suitability of PCI-X 2.0 and 3GIO in the server sector.

Intel is expected to announce a working group defining Serial ATA II, a high-end interface aimed primarily at hard drives. It is expected to have throughput of about 300 Mbytes/s. But that would compete with Serial Attached SCSI, an interface officially announced in November.

The goal of Serial Attached SCSI is to run existing SCSI protocols over the Serial ATA physical layer, preserving software investments in SCSI drives and systems. Whether the two groups can find common ground remains a question.